As to the Robert and Mary you seem to be mentioning, there is, at this time, still no documentation as to her maiden name being Harwell. Harwell and Abernathy researchers far more expert than I or my co-admin have been trying for years to document her and there is still no positive proof that we can link her to a maiden name. We do find a probable Harwell daughter that could be her, but no documentation other than a baptisimal record, so no proof that she even lived to be an adult, much less married the Robert in question.
I assume that since your name is McKinnon, you descend from one or more daughter lines. Our project database does not track most of those. The project database is only concerned with tracking Y-DNA that is directly linked with the surname.
We aren't concerned with autosomal DNA because that is far too new a field, even if Family Tree has a test that is supposed to provide evidence of relatedness via that kind of DNA.